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alexbz

Less FPS when SLI enabled

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Hi,

 

 

I just upgraded my PC with a GTX 980 TI SLI  (I had 780 TI SLI before)

 

With my 780 Ti the FPS where clearly more important when SLI enabled.

 

Now with 980 TI my FPS are less with SLI.

 

 

WIthout SLI

2016-01-09_17-08-42.201619172834.jpg

 

 

With SLI

2016-01-09_17-19-21.20161917292.jpg

 

 

I see that the GPU load are only 30% for each card with SLI! Why the card is so less exploited?

 

Of course without SLI the card is better exploited 50%

 

 

Do I need to do something?

 

I deleted the shaders and the CFG to be sure ...

 

Thanks

 

Dorian

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All this shows is that something else other than the GPU is limiting frame rates. You should try increasing all the GPU-sensitive settings and sliders to the max. See if GPU utilization goes up.

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All this shows is that something else other than the GPU is limiting frame rates. You should try increasing all the GPU-sensitive settings and sliders to the max. See if GPU utilization goes up.

 

Do you mean settings in the p3d app? All is at max, FPS unlimited

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I see the same with medium to high settings on my SLI GTX970SC. Only pushing them with nax settings makes a gain in fps with SLI.

 

Michael Moe

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Do you mean settings in the p3d app? All is at max, FPS unlimited

Try using nVidia Inspector and forcing higher levels of AA. 

 

I assume that you are using P3d 3.1. 4K resolution, dynamic reflections are both killers, as is using ASN with dense clouds. Also, try using as many 4096 textures as possible (clouds, gauges, buildings, runways, etc.). 

 

Anyway, what you are experiencing was predicted a year or so ago when people were clamoring for for an official SLI profile in P3d. Even though P3d makes far better use of the GPU, there are still a lot of threads bound to the CPU and this often "pins" CPU0 at 100% use.

 

Maybe Rob A. has some additional ideas on how to further stress the GPU.

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But you have to take smooth sim into the account. SLI  (or a TITAN X) is a must for eyecandy.

 

Right now i am at gorgeous KSQL with ORBX FTXNCA and Flightbeam KSFO and ORBX KMRY with max settings (water high and DR=low) and the SLI usage goes up to 70-85% on each card and it is so eyecandy and smooth.

 

Still doing 25-35fps in the A2A Comanche 250 and almost the same in the PMDG777  (22-30fps)

 

Will record a video later

 

Michael Moe

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In V3.x SLI only seems to help when using NI SGSS AA ... I've brought this to LM's attention in V3.0 betas but unfortunately no response.  So I recommend not using SLI unless you're using SGSS AA or have some other need/benefit from it.

 

Cheers, Rob.

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SLI also requires some CPU overhead. So if you're in a scenario where you're normally CPU-limited, expected slightly lower performance.

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Try using nVidia Inspector and forcing higher levels of AA. 

 

I assume that you are using P3d 3.1. 4K resolution, dynamic reflections are both killers, as is using ASN with dense clouds. Also, try using as many 4096 textures as possible (clouds, gauges, buildings, runways, etc.). 

 

Anyway, what you are experiencing was predicted a year or so ago when people were clamoring for for an official SLI profile in P3d. Even though P3d makes far better use of the GPU, there are still a lot of threads bound to the CPU and this often "pins" CPU0 at 100% use.

 

Maybe Rob A. has some additional ideas on how to further stress the GPU.

 

 

Hi,

 

Indeed I obtain now about 43-40% GPU usage!  :Party:

 

It's much better i'm at 35 FPS now

 So the GPU is much more stressed, it compute more but the FPS are not increasing.

 

Here my NVI settings :

 

2016-01-09_21-37-48.20161921547.jpg

 

Is it enough?

 

In p3d setting i set the 8 MSAA, 16x anisotropic

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Indeed I obtain now about 43-40% GPU usage! 

 

Try flying thru some Dense clouds/weather or run some high particle density FX in a complex scenery KSEA or KSFO or EGLL at 4K ... watch those GPUs gasp for air :)

 

Cheers, Rob.

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Sorry, but something is not clear for me...

 

I thought FSX/P3D did not even support SLi/Crossfire to begin with. How exactly would you force(?) using it?

 

Particularly interested since I have a pair of R9 290s in crossfire.

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Yes, smog, clouds, rain will do it and peg my three 980's up to 90 percent at times. 

 

 

Rob I really love what LM has done with SLI,,,it works and really hauls (insert your favorite term).

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Try flying thru some Dense clouds/weather or run some high particle density FX in a complex scenery KSEA or KSFO or EGLL at 4K ... watch those GPUs gasp for air :)

 

Cheers, Rob.

 

You're right I reach the 99% with 4k but 15 fps in EGLL and heavy ASN clouds

 

With my native resolution 2560 x 1080 I'm at 25 fps with the PMDG 777  and 33 with another random plane and about 50% GPU charge.

 

 

So i'm able to increase the charge but at the expense of FPS

 

Why the GPU doen't work more to increase FPS?

 

Instead of 50% charge 25fps --->  80¨%   35fps

 

Is it due to my CPU?

 

It's a I7 4930K  OC at 4.4ghz

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Sorry, but something is not clear for me...

 

I thought FSX/P3D did not even support SLi/Crossfire to begin with. How exactly would you force(?) using it?

 

Particularly interested since I have a pair of R9 290s in crossfire.

It doesn't support Crossfire, but it has supported SLI officially for some time now. I'm not sure, but I believe it was nVidia driver 352.86 from last May.

Is it due to my CPU?

 

It's a I7 4930K  OC at 4.4ghz

 

 

 

It's probably everyone's CPU. Take a look at the single thread performance of various CPUs here:

 

https://www.cpubenchmark.net/singleThread.html

 

Sure, one can OC them a little more, but basically they are all going to be in same general range of single thread performance. P3d does use as many cores as are available to load scenery, but one core usually limits performance. GPUs are making much greater performance strides than Intel CPUs are, as Intel previously assumed that adding more physical cores was a general panacea. But it is very challenging to write a multithreaded x86 app that doesn't use one thread to keep track of everything else. This "main" thread tends to be the bottleneck. Further, LM is still fudging around with ACES's old ESP code base, which really wasn't efficiently multithreaded in the first place. 

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It doesn't support Crossfire, but it has supported SLI officially for some time now. I'm not sure, but I believe it was nVidia driver 352.86 from last May.

 

 

It's probably everyone's CPU. Take a look at the single thread performance of various CPUs here:

 

https://www.cpubenchmark.net/singleThread.html

 

Sure, one can OC them a little more, but basically they are all going to be in same general range of single thread performance. P3d does use as many cores as are available to load scenery, but one core usually limits performance. GPUs are making much greater performance strides than Intel CPUs are, as Intel previously assumed that adding more physical cores was a general panacea. But it is very challenging to write a multithreaded x86 app that doesn't use one thread to keep track of everything else. This "main" thread tends to be the bottleneck. Further, LM is still fudging around with ACES's old ESP code base, which really wasn't efficiently multithreaded in the first place. 

 

 

yes you're right.

Autogen, taffic, even the cars on road belong to the CPU

 

CPU is the limiting factor in my case in high autogen, traffic

 

I have to deal with it

 

 

Thanks everybody

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I think that LM has moved the tree autogen to secondary CPU threads and the GPU a while ago (from the 2.2 update page):

 

 

 

Autogen Re-ArchitectureThe instancing system for trees was given a massive overhaul to improve memory usage, to increase performance, and to reduce stutters. The system (VAS) memory footprint per tree was reduced from 276 bytes to 16 bytes (that is a 17x reduction in system memory per tree). Some of the work previously done each frame was completely eliminated while other work was reduced or moved onto background threads and the GPU (graphics card). Visually, trees can now LOD (Level of Detail) in progressively while still scaling in to prevent popping. Random rotation of trees was also fixed, which means that trees will be more varied looking and will again load in at the full density near the camera. A max autogen default flight has had it's system memory reduced by over 550 megabytes!

AI Traffic can be "fixed" by using the Traffic Optimizer app.  Building autogen is still a CPU hog.

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I think that LM has moved the tree autogen to secondary CPU threads and the GPU a while ago (from the 2.2 update page):

 

AI Traffic can be "fixed" by using the Traffic Optimizer app.  Building autogen is still a CPU hog.

 

 

what do you mean by "Traffic optimizer app"?

 

do you have some names?

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I, and I'm sure many others, would be supremely happy if the remaining v3 iterations did nothing more than improve performance, primarily with respect to CPU bottlenecks. With the injection of SLI and more powerful GPUs, GPU performance is now simply a matter of budget and not tech limitations. CPUs, on the other hand...

 

Now that the frothing-at-the-mouth transparent ATC window crowd won their lottery, what else do we need other than better perf?

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It doesn't support Crossfire, but it has supported SLI officially for some time now. I'm not sure, but I believe it was nVidia driver 352.86 from last May.

 

What does the driver have to do with it? My drivers also support crossfire, of course, that's the graphics card driver, but it's the software (fsx/p3d) that has to support sli/crossfire.

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What does the driver have to do with it? My drivers also support crossfire, of course, that's the graphics card driver, but it's the software (fsx/p3d) that has to support sli/crossfire.

 

Carlos,

 

It's both ... there needs to be driver support and software support.

 

Building Autogen is much improved in V3.x compared to V2.x ... however there are some issues when used with 3rd party scenery ... spikes.  LM is aware and have plans to correct in future versions (it is a priority).

 

Cheers, Rob.

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Carlos,

 

It's both ... there needs to be driver support and software support.

 

Building Autogen is much improved in V3.x compared to V2.x ... however there are some issues when used with 3rd party scenery ... spikes.  LM is aware and have plans to correct in future versions (it is a priority).

 

Cheers, Rob.

Right, but what I mean is of the software doesn't have support for it built in, you can of course force it with the drivers, but AMD can do so too, but it's forcing it. That's why I was asking if they did add actual support at some point.

Regarding the driver of course the driver will support sli/crossfire for their cards :)

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Carlos,

 

It's both ... there needs to be driver support and software support.

 

Building Autogen is much improved in V3.x compared to V2.x ... however there are some issues when used with 3rd party scenery ... spikes.  LM is aware and have plans to correct in future versions (it is a priority).

 

Cheers, Rob.

Rob can you post a screenshot of your NV Inspector settings for SLI?

Cheers

Pete

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What does the driver have to do with it? My drivers also support crossfire, of course, that's the graphics card driver, but it's the software (fsx/p3d) that has to support sli/crossfire.

In the nVidia driver control panel, each 3D app has a profile and that profile has one SLI setting that is a bit mask that is specific to each app. Although users have hacked their way through that bit mask setting to force certain apps to work with SLI, only nVidia knows what each bit does and they take each app and decide the best setting for each bit. LM had already made P3d v2 compatible with SLI in early 2015, but they were waiting on nVidia to issue an SLI profile, which they subsequently did with the 352.x driver series.

 

As you know, LM staff have stated repeatedly on their official forum that P3d is designed for nVidia hardware and that they have no intention of making the program Crossfire compatible.

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That's why I was asking if they did add actual support at some point.

 

Still not entirely sure I understand your question ... drivers can't "force" SLI/Crossfire to work ... it's more like "try and see" ... it really depends on how the software is written and what products that software uses (CUDA libraries, Triton SDK, etc.) and if those products also have support for SLI ... it's a long chain of dependency.

 

LM worked with nVidia directly to understand what needs to be done to get SLI working and thanks in part to user feedback directly to nVidia, nVidia provided a profile specific for P3D v2.x (at the time) which has been distributed with all nVidia driver updates going back to P3D 2.x days.  Some minor adjustments were made in P3D V3.0 to remove SLI artifacts.

 

Cheers, Rob.


 

 


Rob can you post a screenshot of your NV Inspector settings for SLI?

 

Sure ... this for V3.x

 

e2ee4ed35568a2cbe91f94540e9a7712.jpg

 

I haven't noticed any different in the "High Quality" vs. "Quality" setting ... so you can ignore that setting.

 

Cheers, Rob.

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